The Complete PS2 Peripheral List
Posted by @ 10:52 AM, EDT
Daily Radar posted an article with the different PS2 peripherals.
A slice:

Bikkuri USB Mouse
Sony's own three-button mouse is USB compatible and has a scroll wheel. There are few games supporting it at the moment (although Armored Core 2 is reputed to support it in menu screens) but it will be indispensable when first-person shooters begin appearing in the US. And naturally it won't be called "Bikkuri" here. Oh, and expect other third-party PS2 mice.